It is beautiful to see the creation of an author; it is beautiful to see a new world created with its own unique history. That is one of the best things about writing: the birth of a world. When you look at any novel or series, the author has created this new world, new realm of thinking, or new extention of our own current world. J. K. Rowling created the wizarding world, Terry Brooks created the land of Shannara, Christopher Paolini created Alagaesia, and we have the opportunity to create our own world.
Once a world is born in the first novel, doors to so many other stories open up. Histories of lands, nation, races, peoples, and characters must now be explored and told because of a new interest.
As I write my fantasy novel, I have countless other story ideas pop into my head. Even though I currently write about Zilthanix and Kestral, I can write stories about their companions, such as Tarya Fairhand, Zarix the Dwarf, Aumundun, and Muyr. I can talk about the history of the Obsidian elves and the Obsidian Dynasty. I know I for sure want to write about a halfling thief named Jaezriin and about the bloody history of the minotaurs.
Once a world is born, a world can be explored. There is thousands and thousands of years of history that can be told. The birth of a world opens up ones writing immensely. It is a master key that opens countless doors.